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(It is usually part of a toogle switch made from thin metal sheet with inner teeth that catch switch notch and outer teeth that slips in panel groove to prevent rotation switch between tightening . But it is also unfortunately direct link for intrusion of water between space under boot through hole to dry side of lid. Switch notch and threads can be also sealed by some sealent , but this ring is good alternative. It sold separately.)

For some microprocessor is that no problem because it can read state Hi/Lo output of switch in ms (better is prolonged version up to 1000 ms because it eliminate debouncing effect ), but if you want to keep Hi/Lo state ,you have to choose latching piezo or add normal piezo switc a latching mechanizm which keep state until next touch.

comercial lights with piezo switches : http://yellowdiving.eu/ PERCH series and http://www.heinrichsweikamp.com/ (buckup , canister video light ) ,piezo switches is also used in diving computers like http://www.shearwaterresearch.com/Basically piezo switch have two wire output . By momentarry pressing When have switch more than 2 wires there is need for power supply for (illumination , some special functions like latch ) switch is basically in NO function (Normaly Opened ). Switch is limited by voltage and current (determinated by FET inside ) and time capability .
Always choose component from producer catalogue with correct code !

ACCELOMETER is special type of piezo switch which senses and measures shocks - acceleration from hold position to acceleration or fading of mass. (equation (F*t = m*dv ; means ; F=m*a)
Small mass is in that case glued on piezo crystal . From switching you need uC with programmed code (or operative amplifier with Schmidt trigger ). Accelerometer is used as switch in http://liquivision.com/ , diving computers. Key is that one accelerometer sealed in housing (best in the centre ) can detects many directions by tapping on enclosure which can simply replace many buttons by tapping directions basic 6 (full 10)
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WET CONTACTS :simple and effective : on two pins split from each-other is always present very small amount of electric tension air is insulation , water sea or fresh is conductor ( with exception of distillated water ). When submerged small current measured in uA flows through contacts and hold on open transistor or FET... When back out of water contacts dry and close circuit. It is possible also to charge lamp through thats contacts .That principe uses computers SCUBAPRO/UWATEC (aladin, Galileo, Luna, Sol) charging through contacts some Fa-Mi torches.

COB LEDS : ( means Chips On Board large leds array intended to street lighting , but because of wide uniform and even light also used for scuba video aplications . http://www.cob-led.com/What-is-cob-LED-chips-on-board.html . A disadvantage of usually presents a high voltage -( more than 36V DC ; more diodes in series voltage rises and more of these series coupled parallel rises of electric current ) .
That usually mean for portable aplications step-up driving circuit which usually don't have such great
Because it was light to illuminate the road was ideal sunlight tend to have the lights COB higher CRI which is also ideal for video .)

http://www.tglobalthermal.com/HEAT CONDUCTIVE FOAM ( filler ( removable ) in space between led driver and enclosure -( it is used at RAM and graphic cards filler between them
and heatsink - irregular shape )

LINEAR DRIVER: drivers that are simple and effective IF it is small power (voltage &current ) drop on them , low drop linear regulators in current driver configuration have to be used .http://led.linear1.org/1led.wizDIRECT DRIVE (resistor my present wire from negative pole or just enclosure resistance ) FOR LED

CONNECTOR '' underwater pluggable electrical connector'' or shorter E/O CONNECTOR ( by original producer ;manufacturer OCEAN TECHNOLOGY SYSTEMS) have contacts exposed to water. CAN BE DISASSEMBLED UNDERWATER but NOT UNDER ELECTRIC POTENTIAL (power OFF)because it can made electric arc and damage contacts.

(after machining SS or aluminium we normaly have viewed microscopically rough surface , that also means increased surface area compared to the smooth surface. Smooth surface contains fewer pores, which could be the anchor for starting corrosion. Secondary aesthetic aspect of electropolishing is reflective mirror look surface . With proper electrolyts all metall materials could be polished.

http://dmcleish.com/CPF/index.html here is no diving lights but it is a collection of very different lights with very different construction approach which I think is sometimes very interesting and helpfull also by our DIY projects.

http://rsbweb.nih.gov/ij/ (beamshot analysis - from image )
How to do it :
0.) download and install program depends from your OS (require java)
1.) take picture and save it in some known format .
2.) open picture with program
3.) go in menue take tool LINE and run it over beamshot (adjust middle point in centre (HOLD left mouse key))
4.) go to ANALYZE menu up and take tool PLOT PROFILE (CTRL+K) and profile should be done

http://www.deepsea.com/download/up_ver4.pdfMANUALS from DEEPSEA PROGRAM which is used for construction deepsea submersible objects (ROV, platforms , piping , bells.....) it is interesting whith which parameters you have to count on for simple geometrical bodies tht will not break down under pressure

Re: DIVE LIGHTING LIBRARY

Im looking for some glass ones that are around 15mm diam mater with a nice short focal length and have a very tight focus??

Lucca, please add this link to the optics section. I don't think many of the divelight subforum readers know about it:http://www.anchoroptics.com/

they have some pretty nice lenses and are really cheap for quality optics (so I've heard, didn't buy from them yet).

@gav, maybe you can find something here that you like. their search engine is nice as well.
Note that tight focus is not something that can be specified for a lens. you want a short focal length to capture as much light as possible. therefor the lens also needs to be big enough to capture the light when the led is in focus. therefor you want lenses with a low f-number.

Re: DIVE LIGHTING LIBRARY

Hi, Lucca.
You replied to me on ScubaBoard today concerning underwater housing for Canon 550D.
Could you please tell me if this momentary toggle switch would work underwater properly without need for additional protection? http://www.apem.com/pdf/MT.pdf

It's from one of your links. I'm also considering toggle switch with lever and hexseal boot with it. Do you have idea which option would be better?
Thank you.

Re: DIVE LIGHTING LIBRARY

Great list, thank you.

Some minor things, Finnsub is not a finnish manufacturer, I believe they are from the Czech Republic. On the other hand there is also Scubamafia from Finland http://www.scubamafia.fi/torches-acc...s-c-27_29.html . I have not seen their torches, but they claim to somehow get a 7° angle with triple XML, I wonder if this is just a bit optimistic or what optics they might use.